A survivor of the shipwreck of immigrants off the Italian coast looks out over the water of Lampedusa in Oct. 2013.

Photo by Tullio M. Puglia/Getty Images

What has already been a particularly lethal week for migrants trying to make their way across the Mediterranean from North Africa to Europe took an even more grisly turn on Thursday, when a religious dispute broke out on a boat traveling from Libya to Italy and ended with a group of Muslim passengers throwing 12 Christian migrants overboard to their deaths.

Italian police said that after the navy intercepted the inflatable craft, officers arrested 15 of the passengers on the boat of 105 people. The alleged assailants, reportedly from Ivory Coast, Senegal, Mali, and Guinea, have been charged with “multiple aggravated murder motivated by religious hate,” the BBC reports. “Eyewitnesses told police … that some of the survivors had formed human chains to avoid a similar fate.”